Apparatus for the charging of blast holes



Nov. 28, 1967 s. A. J. STARK 3,354,771

APPARATUS FOR THE CHARGING OF BLAST HOLES Filed Aug. 17, 1965 3 M 43mmUnited States Patent 3,354,771 APPARATUS FOR THE CHARGING 0F BLAST HOLESSeymour A. J. Stark, 193 St. Georges Road, Observatory Extension,Johannesburg, Transvaal, Republic of South Africa Filed Aug. 17, 1965,Ser. No. 480,328 Claims priority, application Republic of South Africa,Aug. 25, 1964, 64/4,033; Sept. 24, 1964, 64/4,555; Feb. 4, 1965, 65/5778 Claims. (Cl. 86-20) ABSTRACT OF THE DISCLOSURE The apparatus forcharging blast holes is made up of two flexible conduit connected parts.The first part is stationary and consists of a hopper which dischargesinto a gate controlled charge measuring chamber. The chamber dischargesinto a venturi of an air pressure conveyor conduit controlled by aspring loaded valve assembly. The gate is controlled by a push rod of apneumatic rolling diaphragm assembly the piston of which is springloaded. The second part is transportable and includes a pair of aircontrol valves operated manually through a pistol grip trigger assembly.Manual operation of the trigger and control valves opens the airpressure conveyor conduit valve and simultaneously operates the rollerdiaphragm assembly to close the gate into the measuring chamber.

This invention relates to apparatus for the charging of blast holesdrilled in rock with granular type explosive. The apparatus isparticularly suitable for use in underground mining operations.

Devices have been produced to enable measured quantities of granularammonium nitrate to be introduced into blast holes drilled in rock. Ingeneral such devices cannot be easily moved from place to place andrequire more than one workman for this operation.

It is the object of this invention to provide apparatus whereby chargingof blast holes in the manner referred to can be more easily andexpeditiously effected than with presently available means.

In machines of the type above referred to it is also desirable to have ahopper holding a bulk supply of the explosive from which predeterminedquantities may be automatically dispensed. Sliding gates have been triedfor this purpose but have not been wholly satisfactory because of thedifliculty of obtaining adequate clearances for operation of the gateswhile maintaining proper sealing against the pressurised system ofpneumatic conveyance. Rigid hoppers to hold a sufficient quantity of theexplosive are bulky, liable to damage and diflicult to handle inconfined areas such as those encountered in underground miningoperations.

It is a further object of this invention to provide apparatus fordispensing quantities of particulate or some fluid substances which willenable a hopper, not subject to the above disadvantage, to be used whichwill have adequate outlet control into a pressurised system.

According to this invention there is provided blast hole chargingapparatus comprising a hopper with a gate in the base thereof andadapted to be connected into a compressed air supply line, a pneumaticrolling diaphragm and push rod assembly operatively connected to thegate and a control valve assembly for the air supply, and means forremotely controlling the operation of the diaphragm and push rod and thecontrol valve.

Further features of this invention provide for the control of the pistonto be effected through a secondary air supply line and a pair ofmanually operable valves operated in unison through a trigger mechanism.

This invention also provides for the gate to open into a meteringchamber of variable capacity and for the gate to be in the form of arotatable plug above a seal and in the form of part of a hollow spherewith axial pintles integral therewith, the seal being located around adischarge opening from the hopper.

Other features of this invention provide for the hopper to comprisedownwardly directed conical base having a flexible bag secured aroundthe upper part of the base and means for introducing material to bedispensed from the hopper into the bag and for the bag to be made fromrubberised fabric with a firm rib around the mouth of the bag at one endand a hinged lid to the opposite end of the bag where bag and lid arealso supported by firm ribs.

The preferred form of this invention will be described with reference tothe accompanying partly sectional drawings in which:

FIG. 1 is an elevation of the normally stationary part of the apparatus,and

FIG. 2 is a similar view of the manually operable valves for theapparatus on a slightly larger scale.

In the embodiment shown all metal components which may come into contactwith the granular explosive are made of corrosion resistant material.

The apparatus is made in two parts one of which is adapted to remainsubstantially stationary during use while the other consists of thecontrol mechanism and is readily transportable.

The stationary section of the apparatus consists of a hopper 1 having anormally open gate 2 at the bottom thereof discharging into a chamber 3of a size which will house the maximum amount of granular explosiverequired for charging a single blast hole.

Connected to this gate 2 is a pushrod 4 of a pneumatic rolling diaphramassembly 5, the piston of which is spring loaded to the retractedposition in which position the gate 2 in the hopper 1 is maintainedopen. The gate 2 in FIG. 1 is shown in the closed position. The chamber3 has an outlet connected through a venturi located at 6 to dischargeinto a length of flexible hose 7 the free end 8 of which passes throughthe control mechanism and terminates in a length of rigid tubing 9 whichis adapted to be inserted in a blast hole.

The transportable part of the apparatus is supported on a pistol griptype mounting 10.

A trigger assembly 11 is associated with the piston grip 10 to operatein unison a pair of air control valves the inlet one 12 of which isnormally closed and the outlet one 13 normally open. A pair of suitablyprotected small diameter bore flexible tubes 14, 15 lead from the pistongrip mounting 10 back to the stationary part of the apparatus. One ofthe tubes 14 leading to the inlet control valve 12 is connected to themain air supply 16 through the valve assembly 17 on the stationary partand described more fully below and the other tube 15 to the rollingdiaphram and push rod assembly 5.

In this manner operation of the trigger 11 will allow air to pass tomove the pushrod 4 while the normal outlet 18 from the assembly 11 isclosed by operation of the outlet control valve 13. When the trigger 11is released the position of the control valves 12, 13 is reversed sothat air can escape from the assembly 5 and the pushrod 4 Will retractunder the influence of the spring loading. It will be noted that theoutlet part 19 from the mounting 10 is located between the valves 12, 13and forms the connection to the tube 15.

The valve assembly 17 includes a spring loaded valve arranged in such amanner that when the control valve 12 is closed the valve closes thepassage of the main air 3 supply 16 to the tubing 20 which is in directcommunication with the flexible discharge hose 7.

When valve 12 is opened, this causes the valve closing passage 20 toopen as well so that there is a flow of main air through flexibledischarge hose 7 and outlet tube 9 therefor.

The measuring chamber 3 will preferably be made in two telescoping parts21, 22 with a seal 23 between the adjacent surfaces. The two parts 21,22 will preferably be held in telescoping engagement by means ofscrewthreads 23a so that a fine degree of volumetric control over themeasuring chamber 3 can be obtained.

The lower end of this chamber 3 is adapted for, or forms part of, aconnection into a pipeline for pneumatic conveyance as described above.

The upper end of the chamber 3 is secured around the central dischargeopening 24 in the downwardly directed conically shaped base 25 of thehopper 1 for containing a bulk supply of granular explosive. Thedischarge opening 24 has a seal 26 therein forming a seat for a closureplug made in the form of part of a hollow sphere having axial outwardlyprojecting pintles supported in the hopper base 25 and at least one ofwhich projects outwardly from the base for connection throughrightangled lever arm 27 to the piston rod 4 for rotating the plugbetween open and closed positions relative to the discharge opening 24.It will be appreciated that the part spherical plug forms the hopperoutlet gate 2 referred to above.

The base 25 of the hopper 1 preferably has supporting legs 28 for theapparatu attached thereto.

The upper end 29 of the base has a peripheral recess (not shown) formedtherein so that a flexible rubberized fabric bag 30 forming the hopperbody may have the mouth 31 thereof secured, by means of a wire or otherform of circumferential clip 32, in sealing engagement with the base 25of the hopper 1.

The dimensions of the bag 30 are as. in this case, a diameter of about18 inches and a height of about 22 inches and in any event such that thebag 38 will be selfsupporting when charged with particulate material.

The upper end 33 of the bag 30 has a peripherally stiffened lid 34 whichis adapted to engage with co-operating stiffening ribs 35 around theupper end 33 of the bag 30 and the lid is preferably hinged as indicatedat 35 to the bag and means provided for locking the lid 34 to the bag30.

From the above it will be appreciated that when there is no charge inthe hopper 1 the body thereof may be collapsed onto the base 25. Whenthe granular explosive is placed in the bag the body will be raisedthereby only sufiicient to accommodate the charge. Thus the hopper has avariable capacity to suit particular requirements. This is advantageouswhere the apparatus is used in confined spaces such as in undergroundmining operations.

In use it has been found that the form of gate 2 for the hopperdischarge opening 24 provides a good seal between the hopper 1 and thepressurized conveying system in tubing 7 when in the closed position.The shape of the gate also enables it to be easily moved into the openposition through a body of granular charge in the hopper l and this is ahighly desirable feature. Also, when in the open position the gate 2does not interfere unduly with the flow of explosive into the measuringchamber 3.

When used for blasting in mining the hopper l is charged with explosiveand, since the gate 2 is normally open, a measured quantity is fed intothe chamber 3. This quantity is predetermined by the prior setting ofthe two parts 21, 22.

The end of the delivery tube 9 is inserted into the blast hole to becharged and the trigger ll operated. This enables air to move thepushrod 4 in the assembly 5 causing the gate 2 to close in the hopperbase 25 and sequentially results in opening of the valve assembly 17 toenable the main air to carry the explosive from the chamber 3 and packit into the blast hole as required.

When the trigger 11 is released the valve assembly 17 closesautomatically and the hopper gate 2 opens for a fresh charge to enterthe chamber 3.

The machine is then ready for the charging of the next hole.

It will be appreciated from the above that only one operator isnecessary who has complete control of the blast hole charging at therock working face.

What i claim as new and desire to secure by Letters Patent is:

1. Blast hole charging apparatus comprising a hopper having a base and agate in the base, said hopper adapted to be connected to discharge intoa compressed air supply line, a pneumatic rolling diaphragm and pushrodassembly operatively connected to said gate to move the latter, acontrol valve assembly for the air supply, and means for remotelycontrolling the operation of the pushrod and the control valve, saidgate comprising a rotatable plug in the form of part of a hollow spherewith axial pintles projecting therefrom and journaled in said base and aseal retained in said base and cooperating with said gate.

2. Blast hole charging apparatus comprising a hopper having a base and agate in the base, said hopper adapted to be connected to discharge intoa compressed air supply line, a pneumatic rolling diaphragm and pushrodassembly operatively connected to said gate to move the latter. acontrol valve assembly for the air supply, secondary air supply linesconnected to the rolling diaphram and control valve assemblies, a pairof manually operable valves to control air in the secondary supply linesand a trigger mechanism to operate the manually operable valves inunison. a metering chamber of variable capacity interposed between saidhopper gate and the connection into the compressed air supply line.

3. Blast hole charging apparatus comprising a hopper having a base and agate in the base formed as a plug of part hollow spherical shape withaxial pintles projecting therefrom and a seal in the base for the plug,a metering chamber of variable capacity positioned below the gate andhaving the opposite end adapted for connection into a compressed airsupply line, a pneumatic rolling diaphragm and pushrod assemblyoperatively connected to said gate to move the latter, a control valveassembly for the air supply and means for remotely controlling theoperation of the pushrod and the control valve.

4. Blast hole charging apparatus as claimed in claim: 3 including alever connecting one of the plug pintles to the pushrod of the rollingdiaphram assembly.

5. Blast hole charging equipment as claimed in claim 3 in which themetering chamber is made in two telescoping parts with screwthreadengagement between these two parts.

6. Blast hole charging apparatus comprising a hopper having a downwardlydirected conical base and a flexible bag with a mouth secured around theupper part of the base, means for introducing material to be dispensedfrom the hopper into the bag, a gate in the base formed as a plug ofpart hollow spherical shape with axial pintles projecting therefrom anda seal in the base for the plug, a metering chamber of variable capacitypositioned below the gate and having the opposite end adapted forconnection into a compressed air supply line, a pneumatic rollingdiaphram and pushrod assembly operatively connected to said gate to movethe latter, a control valve assembly for the air supply and means forremotely controlling the operation of the pushrod and the control valve.

7. Blast hole charging apparatus as claimed in claim 6 in which the bagis made from rubberized fabric with a firm rim around the mouth of thebag, a removable lidprovided at the other end of the bag and peripheralstiffening ribs for this end of the bag and the lid.

8. Blast hole charging apparatus comprising a hopper having a base and agate in the base, said hopper adapted to be connected to discharge intoa compressed air supply line, a pneumatic rolling diaphragm and pushrodas sembly operatively connected to said gate to move the latter, acontrol valve assembly for the air supply, secondary air supply linesconnected to the rolling diaphragm and control valve assemblies, a pairof manually operable valves to control air in the secondary supply linesand a trigger mechanism to operate the manually operable valves inunison, said hopper consisting of a downwardly directed conical basewith the gate at the part of the base and means whereby material to bedispensed from the hopper may be introduced therein.

References Cited UNITED STATES PATENTS 2,834,245 5/1958 Osborne 86203,125,925 3/1964 Ljungberg 86-20 3,227,093 1/1966 Taplin 103150 FOREIGNPATENTS 704,354 2/1965 Canada.

SAMUEL FEINBERG, Primary Examiner.

apex thereof, a flexible bag secured around the upper 15 P, A, SHANLEY,A si t t E mi

1. BLAST HOLE CHARGING APPARATUS COMPRISING A HOPPER HAVING A BASE AND AGATE IN THE BASE, SAID HOPPER ADAPTED TO BE CONNECTED TO DISCHARGE INTOA COMPRESSED AIR SUPPLY LINE, A PNEUMATIC ROLLING DIAPHRAGM AND PUSHRODASSEMBLY OPERATIVELY CONNECTED TO SAID GATE TO MOVE THE LATTER, ACONTROL VALVE ASSEMBLY FOR THE AIR SUPPLY, AND MEANS FOR REMOTELYCONTROLLING THE OPERATION OF THE PUSHROD AND THE CONTROL VALVE, SAIDGATE COMPRISING A ROTATABLE PLUG IN THE FORM OF PART OF A HOLLOW SPHEREWITH AXIAL PINTLES PROJECTING THEREFROM AND JOURNALED IN SAID BASE AND ASEAL RETAINED IN SAID BASE AND COOPERATING WITH SAID GATE.